Patent Literature 1 describes a “drum-in-disk brake device that integrally forms a brake disk rotor with a brake drum, in which braking is performed by a disk brake device during running and braking is performed by a drum brake device during parking”. In such a brake device, a service brake and a parking brake are operated independently, and thus the service brake and the parking brake do not interfere with each other.
The applicant develops an electric braking device in which service braking (braking performed by a driver's operation to step on a brake pedal) and parking braking (braking to maintain a halted state of a vehicle) are performed by a single electric motor, as described for example in Patent Literature 2. Here, the parking brake exhibits its function by restraining a motion of an electric motor MTR by a lock mechanism LOK configured of a ratchet wheel RCH and a hook member TSU. Moreover, to suppress interference between the service brake and the parking brake in the control of the electric motor MTR, larger one of a service brake target value Ims and a parking brake target value Ipk is selected as a final target value Imt by a selecting means SNT in determining a target electricity amount of the electric motor MTR.
In the electric braking device of Patent Literature 2, a situation will be assumed in which a driver switches a parking brake switch (parking switch) PSW from an off state to an on state under a state in which the driver is operating a braking operation member (brake pedal) BP at an excessively strong degree. In this case, an unnecessarily excessive force is applied to a caliper against a retaining force that maintains the halted state of the vehicle. Thus, strength of the caliper must be sufficiently ensured, which may bring forth size and weight increases in the electric braking device.
Further, as described in Patent Literature 2, in a case where the control of the electric motor is adjusted at a level of the target electricity amount (at a calculation stage), a force Fba by which a friction member MSB presses a rotary member KTB is affected by a power transmission efficiency from the electric motor MTR to the friction member MSB. For example, in a case where a viscosity of lubricant becomes high in an extremely low temperature and the power transmission efficiency is thereby reduced, a delay may be generated in the operation (engagement operation or release operation) of the parking brake.